Ensure the song isn't already on the playlist. You can see the entire playlist on a single page here.

Under normal circumstances any track longer than 10 minutes will be rejected. That doesn't mean you should send 10 minute loops of a 60 second clip though.

Please don't send stuff like this. You can send troll-y stuff if you really want but don't get your hopes up.

I enjoy anime myself too, but consider submitting instrumentals. We don't need to listen to Japanese for most of our time here.

Song names are automatically parsed. There are two routes you can go, either use proper artist and title tags OR have the filename be in the format "composer - track (ost)". It doesn't matter which one you use, but the parser will ignore the filename if the tags are set.